1. Field of the Invention
This application relates to an electrical circuit, and in particular, to a shutdown circuit for half-bridge converters.
2. Discussion of the Art
The on-off operation of half-bridge converters has traditionally been accomplished by analog signals. However, use of digital signals to control the on-off operation of loads, such as lamps, is now known in the art. In one approach, electromagnetic relay switches are used. Electromagnetic relays, however, are bulky due to their large size. They are also generally slow.
In another approach, solid state relays have been used. Solid state relays, however, are expensive. Further, the use of solid state relays decreases the efficiency of the circuit because of the power dissipation which occurs when the relay is on.
Accordingly, a need exists for a more efficient and less expensive way to control operation of loads using digital signals.
An exemplary embodiment of the present invention concerns a power supply circuit configured to control operation of a load. The power supply circuit includes a converter configured to convert a DC signal to an AC signal, a drive circuit connected to the converter to control operation of the converter, and a shutdown circuit connected to the drive circuit to turn off the converter. The shutdown circuit includes a diode and a switch.
This circuit has a number of advantages over the prior art. The circuit is integrated and less expensive.
Another advantage resides in the fact that this power supply circuit is more efficient than the prior art circuits which utilize relays.